Thoracic Space Disease in Dogs

TSD is a collective term for the accumulation of air, or fluid, within the chest cavity.

Examples include:

• Pneumothorax - Air accumulation in the chest cavity
• Chylothorax - Accumulation of chyle - a milky, fatty liquid carried in the lymphatic system
• Pyothorax - Pus accumulation in the chest cavity
• Transudate/modified transudate (Pleural effusion/hydrothorax) - leakage of cellular fluid out of the cells into the chest cavity
• Hemothorax - Accumulation of blood in the chest cavity

Accumulation of air or fluid in the thoracic space (chest cavity) results in significant dysfunction of the heart and lungs, which is fatal if untreated. TSD is a common cause of respiratory distress in dogs, especially senior dogs. Animals with breathing difficulty, collapse and blue/purple gums require emergency veterinary attention.

Thoracic Space Disease (TSD) in dogs is a serious condition regardless of the underlying disease.

Symptoms result from an increase in pressure in the thoracic space which results in reduced filling of the heart and collapsing of the lungs. Mild or slowly progressive disease may be well tolerated in the early stages and lead to persistent, low grade decline such as weight loss and exercise intolerance. Fast onset, or severe TSD, results in significant symptoms and may be fatal if untreated.

There are varying types of TSD that share common underlying causes

TSD presents similarly regardless of the underlying disease process.

Diagnosis of TSD focuses on identification of the underlying disease process and includes:

• Physical examination
• Needle sample of the chest cavity to detect air or fluid

Testing of chest fluid such as:

• Microscopic examination
• Culture and sensitivity
• Blood work
• X-rays
• CT scan
• Heart ultrasound (echocardiography)

Treatment options vary depending on the specific accumulation present in the thoracic space and the underlying disease mechanism. Options include:

• Thoracocentesis - draining fluid or air from the chest to relieve pressure on the heart and lungs
• Placement of a chest drain to allow repeat drainage until the disease trigger is resolved

Treatment specific to the underlying disease includes:

• Antibiotics
• Pain relief
• Cancer treatment
• Treatment of clotting disorders
• Treatment of heart disease
• Surgery

Outcome depends on the ability to treat the initial build up of fluid or air and definitive treatment of the underlying disease. Many of these conditions are severe, chronic, or progressive and some are fatal or result in humane euthanasia due to poor prognosis or quality of life.

The initial drainage of fluid or air in the chest cavity immediately improves symptoms but cases often recur depending on the underlying disease process. Long term prognosis varies: If the initial trigger is resolved, such as injury or infection, then the prognosis is good. Severe, or ongoing conditions such as tumors, inherited, or idiopathic causes carry a guarded prognosis.

Prevention of individual cases is usually not possible however, reducing recurrence may be possible by

• Regular monitoring
• Repeat chest X-rays
• Low fat diets

TSD is moderately common in dogs

• Thoracocentesis
• Placement of a chest drain
• Treatment specific to the underlying disease
• Antibiotics
• Pain relief
• Cancer treatment
• Treatment of clotting disorders
• Treatment of heart disease
• Surgery